In the manufacture of electrical capacitors, layers of a metallic material separated by a layer of a dielectric material are wound in a roll. The capacitor roll is placed in a tube which is usually of paper, such as Kraft paper with a typical thickness of 0.015", and which is spiral wound. After the paper tube is formed, the periphery of one of its ends is bent inwardly to provide a mounting lip for the capacitor roll so it will not become displaced from the tube. The tube with the capacitor roll therein is placed within a metal outer housing, or can, with the lip end facing toward the bottom of the can. The capacitor is then impregnated with dielectric fluid and oil and the can is thereafter sealed.
While a spiral wound paper tube is satisfactory, it is relatively costly and inconvenient to use. For example, different size tubes may require different manufacturing procedures. Also, if a large quantity of tubes have to be stored, substantial space may be required. Further, due to the thickness of the spiral wound paper forming the tube, the inwardly bent lip is rather bulky and increases the vertical height of the tube. This extra height creates difficulty during automatic assembly.